This application claims the priority of German Patent Document 100 15 573.1, filed in Germany on Mar. 29, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and a device for the cylinder-specific determination of spark failures on a reciprocating engine through a classification process based on the crankshaft rotational velocity (r.p.m.), wherein before the classification process the information on the crankshaft r.p.m. is subjected to a transformation, which separates the information into uncorrelated components.
Within the framework of the monitoring process for the engine condition, it is important to recognize spark failures among the individual cylinders of an engine in order to be able to influence the resulting uneven running behavior of the engine by influencing the combustion process in the individual cylinders.
From European Patent Document EP 0474652 B1, corresponding U.S. Pat. No. 5,255,560 we know of a method that measures the erratic running values of an engine under consideration of the time frames of the combustion cycles of different groups of cylinders. The erratic running value calculated this way is then utilized in an idle adjustment process.
In German Patent Document E 19548604 C1, corresponding U.S. Pat. No. 5,709,192 a method for determining non-uniform cylinder torques based on engine r.p.m. is described. On the basis of the signal issued by the speed governor, the torque moments of the individual cylinders are determined. When conducting the method it is important that individual cylinders of the engine can be shut off selectively during operation of the engine.
The method described in patent German Patent Document DE 19633066 C2, corresponding U.S. Pat. No. 6,082,330 allows the deduction of various parameters from the curve of the current crankshaft r.p.m. in a cylinder-selective and r.p.m.xe2x80x94dependent manner; these parameters are correlated to the respective medium pressure of the engine""s combustion chambers.
The method described in German Patent Document DE 19540675 C1 involves an estimation process for the torque of a reciprocating engine, based on a physical-mathematical example, from the crankshaft r.p.m. Through a modeling process, the gas moment of selected cylinders of the engine is deduced from the r.p.m. values. By subtracting a mean value from the cylinder-selective values a residuum is obtained, which indicates a combustion failure when exceeding a threshold value. We are familiar with methods for differentiating and/or classifying various signals from the areas of data processing and pattern recognition. Common encyclopedias (e.g. H.-J. Schneider xe2x80x9cLexikon der Informatik und Datenverarbeitungxe2x80x9d [Encyclopedia of Information Systems and Data Processing], 3rd Edition, 1991, R. Odenbourg Publishing Co., Munich, Germany) define the basic terms, and text books (such as M. Barkat, Signal Detection and Estimation, 1991, Artech House Inc. or S. Haykin, Unsupervised Adaptive Filtering, Volume 1: Blind Source Separation, John Wiley and Sons, 2000) describe specific methods. Suitable classification processes for pattern recognition tasks are mentioned in text books on numerous occasions, e.g. J. Schxc3xcrmann, Polynomklassifikatoren fxc3xcr die Zeichenerkennung (Polynomial Classification processes for Sign Recognition), 1977, R. Oldenburg Publishing Co., Munich, German; this one is adjusted specifically to optical character recognition.
An object of the invention and apparatus is to find a novel method for the cylinder-specific determination of spark failures on a reciprocating engine, wherein a classification unit uses measurement data that contains information about the number of crankshaft revolutions.
The object achieved according to preferred embodiments of the invention with the help of a classification unit in which the data are subjected to a pre-processing step and classified with the help of a classification process, wherein within the framework of the pre-processing step the data are subjected to a transformation, which separates this data into uncorrelated components.
The present invention provides for a simple method of transforming the reading of signals from a gear ring arrangement on the crankshaft to a recognition of spark failures, and identification of incorrectly functioning cylinders which eliminates the requirement for complex models or the requirement for significant computer power or significant operational knowledge concerning the mechanics of propulsion engine. This method involves a diagnostic tool based on the transformation of vectors containing related signals in an orthogonal space and the reduction in the dimensionality of the feature space to be handled by a classifier.
In a beneficial manner, the invention permits the recognition of spark failures and the identification of incorrectly functioning cylinders even on engines that have a time-overlapping effect of the individual cylinders"" pulse responses to the r.p.m. signal (e.g. 16-cylinder engines). The complex vibration behavior of the crankshaft caused by this does not have to be simulated with comprehensive mathematical examples (differential equations).